The present invention relates to packers and anchors used in oil and gas wells. In one aspect, the invention relates to radially expandable rings for use in a packer or anchor to achieve a metal to metal seal and/or anchor of an inner tubular within a casing, for example, a well bore casing. In another aspect, the present invention relates to a packer or anchor with a sleeve that can be radially expanded in response to pressure until it seals and/or anchors against the inside surface of the outer tubular, for example, a well bore casing.
During the course of completing and producing an oil or gas well, the annulus between the well bore casing and an interior tubular, for example a work string or a production string, is commonly required to be sealed. One type of such an annular seal is referred to as a packer. Packers often employ elastomeric sealing rings that have a running diameter while tripped to the desired location in the well bore and then are expanded radially outward by some mechanism to seal against the inside of the well bore casing. Elastomeric seals suffer from several drawbacks. They often cannot withstand prolonged high temperature and/or high pressure. The seals may also extrude into gaps sacrificing the sealing quality. Additionally, elastomeric seals are susceptible to swabbing off of the packer when the packer is tripped down hole due to the fluid flow across the elastomeric seal.
U.S. Pat. No. 5,511,620 to Baugh discloses a packer that combines a metal to metal seal with a conventional elastomer seal. A metal cylinder with radially extending ridges is expanded radially outward until the metal ridges engage the inside of the well bore. This design suffers from at least three drawbacks. First, because the ridges are part of the cylinder, they must be made from the same relatively soft ductile material as the cylinder and therefore will not imbed sufficiently into the harder inside of the well bore casing. Secondly, as the cylinder expands, the ridges must deform plasticly as they likewise expand which dulls any sharp edge that may have been machined onto the ridges. Thirdly, the cylinder is expanded with a tapered piston that has a circular cross-section. As this tapered piston expands the cylinder radially outward, the cylinder may not conform to out-of-round well bore casing or a defect in the casing wall.
Therefore, a need exists for an expandable seal that can seal the annulus between the well bore casing and an inner tubular without the drawbacks of the metal to metal seal of the ""620 patent or the conventional elastomeric seals. A need also exists for a packer metal to metal seal that can conform to out of round holes for proper sealing.
Additionally, the inner tubular may need to be anchored within the casing with or without sealing the annulus. Therefore, a need exists for a slip that can be employed alone or with metal to metal sealing of an inner tubular within a casing.
The present invention provides an expandable metal to metal seal and/or anchor that overcomes the above discussed deficiencies. In one embodiment of the present invention, a metal cylinder with separate rings is radially expanded by a fluid so that the cylinder will conform to the inside of the well bore casing and the rings expand as the waviness accommodates the expansion of the cylinder while the rings do not deform plasticly thereby retaining any sharp edges. For sealing, the rings are continuous and wavy in the axial direction while for solely anchoring, the rings can be split rings without any waviness in the axial direction.
In another embodiment, the present invention provides an inflatable cylinder that can conform to out of round casing and provide a metal to metal seal.